Hard metal composition



Patented 23, 19 11.9

arrest rarest-r caries naan METAL (COMJPU SETION Richard Kiefier, Tyroll,

Austria, assignor to American Cutting Alloys, inc, New York, N. 222, a corporation of Delaware 3 Glaims.

This invention relates to a hard metal alloy, in particular for tools and other working appliances.

More in particular, the invention is concerned with hard metal tool alloys containing tantalum carbide in considerable amounts.

It is an object of the invention to improve the hardness of hard metal alloys containing tantalum carbide in substantial amounts.

It is another object of the invention to produce a hard metal alloy of improved hardness and toughness containing tantalum carbide in considerable amounts.

It is still another object of the invention to l render hard metal tool alloys containing tanta- 5 lum carbide in considerable amounts suitable for machining steel and other materials which, like steel, give long chips when machined.

These and other objects of the invention will 0. be more clearly understood when the specification further proceeds.

In the production of hard metal tool alloys, in particular for machining long chip forming materials such as steel, many attempts were made to produce alloys being as hard as possible and of the lowest possible heat conductivity. Such materials, as experience has shown, are most suitable for turning, milling, planing and similar chip forming machine Work.

Hard metal alloys have been suggested for this purpose consisting substantially of tungsten carbide, and it was suggested to add titanium carbide in order to improve the properties of these alloys referred to above. It has also been suggested to add to these carbides various other hard carbides which have proven to some extent suitable for the purposes referred to above.

In particular, hard metal alloys have been suggested containing considerable amounts of tantalum carbide which was cemented by suitable auxiliary metals, imparting toughness to the alloy. Such hard metal alloys were, however, of relatively little hardness.

According to the present invention, a hard metal alloy for tools and other working appliances is made of a major portion of tantalum carbide and/or niobium carbide (which is also called columbium carbide) whereas a minor portion of the alloy consists of titanium carbim, tungsten carbide and/or molybdenum carbide.

59 Of these carbides which are to be present as a minor portion of the alloy, titanium carbide is always present in an appreciable amount. Of the other carbides there may be present about 1% to These carbides are combined with tough auxiliary metal, preferably of the iron group, thou; other metals such as chromium may be added small amounts. Auxiliary metal should be pre ent in amounts of about 2% to 20%.

In the preferred form of the invention ti hard metal alloy is sintered, and the auxilia metal substantially cements the carbide.

Although the alloy can be manufactured in a: desired way it may be mentioned that first t carbide may be formed, then comminuted a1 admixed to the powdery auxiliary metal wher upon the mixture can be pressed and shaped a1 highly sintere'd.

The carbide may be combined into mixed cry tals, which are a solid solution, before the au iliary metal is admixed, or the formation of solid solution of the carbides may be caused permitted to some extent during the sinteri: process.

In particular, if tantalum carbide and IiiOblll carbide are used, they can be transformed in mixed crystals entirely or to a substantial exter for instance, at least 10% of these carbides shot be transformed into mixed crystals.

It is to be understood, however, that the i vention is not limited to the use or formation mixed crystals.

Niobium carbide is of properties similar those of tantalum carbide. Indeed, niobium pt tains to the same chemical group as tantalt does and therefore has quite similar characte istics.

Therefore, niobium carbide can be substitut in part, for tantalum carbide for the purposes this invention. It has been proven particular suitable to form mixed crystals of these carbid Such mixed crystals of carbides exceed as to th hardness that of the components.

In order to suit hard metals containing tani lum carbide to various demands, other carbiC may be added besides titanium carbide where either the heat conductivity, or the resistar against oxidation, or hardness, or toughness, other characteristics of the alloy can be afiecl individually or simultaneously.

If, for instance, molybdenum carbide is add the average hardness of the carbide present increased. If tungsten carbide and chromll carbide are added, the toughness of the all can be increased whereas zirconium carbide, added, somewhat reduces the heat conductivi Sometimes also small additions of vanadium c: bide are of advantage.

Such additional carbides can be present amounts up to about 20%. If two of such or LIB added simultaneously, their total, on rage, may amount to not more than 20%. following are compositions which have advantageous in practice in one or the espect.

Emmple 1 Per cent mm carbide 50 im carbide 25 .enum carbide 10 15 alloy is of great hardness and particularly for iine grinding or turning steel.

Example 2 Percent mm carbide 60 im carbide 5 n carbide 11 en carbide 20 4 sintered alloy is of particular toughness lted for use in machinw which are liable ite.

articular, this alloy can be used in older can be decreased or increased by prcportioning the amount of auxiliary metal.

What I claim is:

1. A' sintered hard metal alloy, particularly adapted for tools and other working appliances, substantially consisting of about 60% tantalum carbide, about 5% titanium carbide, about 11% niobium carbide, about 20% tungsten carbide and about 4% auxiliary metal substantially of the iron group.

2. A hard metal composition, particularly adapted for tools and other working appliances, substantially consisting 01' 50% to 91% tantalum carbide and niobium carbide, 8% tantalum carbide and 11% niobium carbide as a minimum, about 5% to 20% titanium carbide and about 1% to 20% carbide selected from a group consisting of tungsten carbide and molybdenum carbide, said carbides of normal crystalline structure and present in finely divided state, and about 2% to 20% auxiliary metal of the eighth group of the periodical system and substantially selected from the iron group thereof.

3. A sintered hard metal composition, particularly adapted for tools and other working appliances, substantially consisting of 50% to 91% tantalum carbide and niobium carbide, 8% tantalum carbide and 11% niobium carbide as a minimum, about 5% to 20% titanium carbide and about 1% to 20% carbide selected from a group consisting of tungsten carbide and molybdenum carbide, said carbides of normal crystalline structure combined into mixed crystals in substantial amount and present in finely divided state, and about 2% to 20% auxiliary metal of the eighth group of the periodical system and substantially selected from the iron group thereof.

RICHARD KIEF'FER. 

